1. Field of the Invention
This invention relates to a portable telephone set, and more particularly to a portable telephone set of the foldable type.
2. Description of the Related Art
Conventionally, a foldable telephone set of the type mentioned is constructed such that a telephone set body is divided into two sections, including a body section and a cover section, and these two sections are interconnected by means of a hinge mechanism or the like. Thus, when the telephone set is to be used, the cover section is opened relative to the body section, but when the telephone set is not used, they are folded to facilitate transportation of the telephone set.
By the way, in a portable telephone set in recent years, when a call to the user of the telephone set is terminated, if the user makes a response to the terminated call by operation of a key or the like, then a speaking condition with an originating person is established. Then, when it is intended to end the speech, a key is manually operated. The portable telephone set has a response holding function for notifying, when the user cannot make a response when a call is terminated, this fact to the originating person. Also, the portable telephone set has a speech holding function for temporarily holding, when it is in a speaking condition, the speech. The response holding function and the speech holding function are performed each by way of an operation of a key.
In the conventional portable telephone set of the construction described above, in order to cause, for example, the speech holding function to operate, it is required to operate a predetermined key during speech. However, since a key of a telephone set of the type described is small, the operability is so low that another key may be manually operated in error. If a wrong key is manually operated in this manner, then the speech may be disconnected. On the other hand, a key may be manually operated in error while the speech holding function is operating, and this may cancel holding of the speech or cause interruption of the speech.
Particularly, since the body section and the cover section of a foldable portable telephone set are formed with a comparatively small thickness, switches having a comparatively small height are progressively used for keys disposed on the cover section. Where such switches are employed, not a key to be operated but another adjacent key is likely operated manually, resulting in such troubles as described above. Consequently, such troubles as described above are liable to take place.